Building my own solar power system

I see 7k€ for 12kWp, retail, for a diy ground install set for our summer house. That's before 4k€ in subsidies. No net metering, and feedin compensation is capped at 0.02€/kWh. But at 3k€ net, who cares? Even with the low electricity rates here, this makes sense. Even for a summer house!

Great to see DIY early adopters getting great savings here. I think the bigger trend here is lower cost, commoditization, and it eventually becoming a no-brainer for people that have the opportunity/space to be running their own micro grids for cost reasons. The cost of what you need here is still quite high. But making things easier to plug together helps. And of course component cost is coming down.

For example, you can buy kits on amazon for powering your shed or boat and it's essentially a smaller version of what you would put on your house. No electricians needed. No permits required. Here in Germany you can buy balcony solar kits in the supermarket. They only deliver a few hundred watts of power but it's plug and play. And you can get a nice little subsidy to do that. Some of these kits only cost a couple of hundred euro.

I could see that eventually adding a microgrid to a building is not going to break the bank. Car batteries are much larger than what goes in a house and kwh prices are trending well below 100$/kwh now. Meaning it should not cost tens of thousands to get a couple of tens of kwh to store energy. Inverters shouldn't break the bank either. The going rate for solar panels is around 200$.

Mostly current prices for home setups are much higher than the component cost mainly due to regulations, labor cost, certifications, etc. If you go off grid, you can just DIY and you end up much closer to the component cost. But of course long term both component cost and other cost are coming down. With the exception of labor cost probably. Though the skills needed will become more common and you might be able to do a lot of work yourself.

Batteries are dropping fast in price, but for the USA, they might be going up because of tariffs. Neatly sidestepping that:

I have a powerwall 2 with 5kw panels, which I've had since about 2021. At the time it was the biggest, cheapest, had a grid isolation mode, and could be mounted outside. (I didn't trust tesla back then, and I sure as shit don't now. Moreover, once it catches fire, that shit aint going out anytime soon)

It still cost about £7k installed.

From about march/april to end of october, we are power sufficient (london, even with rainy days, gas hot water though.)

If I were to get a new system, 13kwhr of battery is something like £2k, plus inverter/charger.

The panels are dirt cheap, to the point where the scaffolding costs more than the panels. (and the mounts.)

capex vs opex

I have a minor interest in this subject as well, and after some thinking I realized that my personal solar interests are best served by electro-mechanical harvesting of solar energy, first and foremost .. since a full-blown EV solar rig would require the purchase of components I cannot myself personally make very easily.

This summer I'm building a solar oven to cook bread and veggies with .. and if this works well, I'll build a solar death ray to play with while I wait for lunch.

It seems to me that this is a potential route for the popularization of off-grid/local-energy-harvesting movements to gain more traction. Sure, its nice to have a whole roof full of PV panels and a battery bank to sip juice from now and then, but this still requires a heavy investment in foreign-originated parts and materials.

A solar oven/solar death ray, however, is a lot more feasible to produce locally.